From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754881AbbDMWIR (ORCPT ); Mon, 13 Apr 2015 18:08:17 -0400 Received: from www.linutronix.de ([62.245.132.108]:33941 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751318AbbDMWIO (ORCPT ); Mon, 13 Apr 2015 18:08:14 -0400 Date: Tue, 14 Apr 2015 00:08:23 +0200 (CEST) From: Thomas Gleixner To: Arnd Bergmann cc: LKML , Peter Zijlstra , Ingo Molnar , "David S. Miller" , dingtianhong , Zhangfei Gao , Dan Carpenter , netdev@vger.kernel.org Subject: Re: [patch 4/5] net: hip04: Make tx coalesce timer actually work In-Reply-To: <3040901.Bp3bfgc1te@wuerfel> Message-ID: References: <20150413210009.682000343@linutronix.de> <9614284.QjZ4xls6zV@wuerfel> <3040901.Bp3bfgc1te@wuerfel> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 14 Apr 2015, Arnd Bergmann wrote: > On Monday 13 April 2015 23:42:03 Thomas Gleixner wrote: > > > > > > Question: this looks to me like it sets both the minimum and maximum > > > time to priv->tx_coalesce_usecs/2, when the intention was to set > > > the minimum to priv->tx_coalesce_usecs/2 and the maximum to > > > priv->tx_coalesce_usecs. Am I missing something subtle here, or did > > > you just misread my original intention from the botched code? > > > > Yes, I missed that. Simple fix for this is: > > > > unsigned long t_ns = priv->tx_coalesce_usecs * NSEC_PER_USEC / 2; > > > > hrtimer_start_range_ns(&priv->tx_coalesce_timer, ns_to_ktime(t_ns), > > t_ns, HRTIMER_MODE_REL); > > Ah, good. I have to admit that I'd probably make the same mistake > again if I was to do this for another driver and you hadn't sent > the fix. The hrtimer_set_expires_range() function just looked like > it had been designed for the use case I was interested in ;-). > > Any idea how to prevent the next person from making the same mistake? Yes. Documentation :) Thanks, tglx